Re: [PATCH] convert cnt32_to_63 to inline

[Steven Rostedt]

On Tue, 11 Nov 2008, Peter Zijlstra wrote:

> On Tue, 2008-11-11 at 22:31 +0000, David Howells wrote:
> > Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx> wrote:
> > 
> > > @@ -52,18 +57,22 @@ unsigned long long sched_clock(void)
> > > ...
> > > +	preempt_disable_notrace();
> > 
> > Please, no!  sched_clock() is called with preemption or interrupts disabled
> > everywhere except from some debugging code (lock tracing IIRC).  If you need
> > to insert this preemption disablement somewhere, please insert it there.  At
> > least then sched_clock() will be called consistently.
> 
> Agreed. You could do a WARN_ON(!in_atomic); in sched_clock() depending
> on DEBUG_PREEMPT or something to ensure this.

It would also be nice if this requirement (calling sched_clock with 
preemption disabled) was documented somewhere more obvious.

Doing as Peter suggested, adding a WARN_ON and documenting that this must 
be called with preemption disabled, would be nice.

-- Steve

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/